College of Biomass Science and Engineering, Sichuan University, Chengdu, 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, 610065, China.
State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
Food Microbiol. 2021 Aug;97:103750. doi: 10.1016/j.fm.2021.103750. Epub 2021 Jan 21.
The accumulation of ethanol has a negative effect on the viability and fermentation performance of microorganisms during the production of fermented foods because of its toxicity. In this study, we investigated the effect of co-culture with Tetragenococcus halophilus on ethanol stress resistance of Zygosaccharomyces rouxii. The result showed that co-culture with T. halophilus promoted cell survival of Z. rouxii under ethanol stress, and the tolerance improved with increasing co-culture time when ethanol content was 8%. Physiological analysis showed that the co-cultured Z. rouxii cells maintained higher intracellular content of trehalose and amino acids including tyrosine, tryptophan, arginine and proline after 8% ethanol stress for 90 min. The membrane integrity analysis and biophysical analysis of the cell surface indicated that the presence of ethanol resulted in cell membrane damage and changes of Young's modulus value and roughness of cell surface. While the co-cultured Z. rouxii cells exhibited better membrane integrity, stiffer and smoother cell surface than single-cultured cells under ethanol stress. As for transcriptomic analyses, the genes involved in unsaturated fatty acid biosynthesis, trehalose biosynthesis, various types of N-glycan biosynthesis, inositol phosphate metabolism, MAPK signaling pathway and tight junction had higher expression in co-cultured Z. rouxii cells with down-regulation of majority of gene expression after stress. And these genes may function in the improvement of ethanol tolerance of Z. rouxii in co-culture.
乙醇的积累会对发酵食品生产过程中微生物的活力和发酵性能产生负面影响，因为它具有毒性。在这项研究中，我们研究了与嗜盐四联球菌共培养对鲁氏酵母乙醇胁迫抗性的影响。结果表明，共培养嗜盐四联球菌促进了鲁氏酵母在乙醇胁迫下的细胞存活，并且当乙醇含量为 8%时，共培养时间的增加提高了耐受力。生理分析表明，共培养的鲁氏酵母细胞在 8%乙醇胁迫 90 分钟后，细胞内海藻糖和包括酪氨酸、色氨酸、精氨酸和脯氨酸在内的氨基酸含量保持较高。细胞膜完整性分析和细胞表面的生物物理分析表明，存在乙醇会导致细胞膜损伤以及杨氏模量值和细胞表面粗糙度的变化。然而，在乙醇胁迫下，共培养的鲁氏酵母细胞表现出比单培养细胞更好的细胞膜完整性、更硬和更光滑的细胞表面。至于转录组分析，参与不饱和脂肪酸生物合成、海藻糖生物合成、各种类型的 N-聚糖生物合成、肌醇磷酸盐代谢、MAPK 信号通路和紧密连接的基因在共培养的鲁氏酵母细胞中表达较高，而大多数基因在胁迫后表达下调。这些基因可能在共培养中提高鲁氏酵母的乙醇耐受性方面发挥作用。
